No problem. Here's a shopping list of what you need.
1x piece of wood. It needs to be about 2.5 to 3ft long.
1 length of washer tube. The tube I bought was about 5mm dia. It needs to be twice as long as the timber, plus enough spare to reach from where you'll stand the manometer to to the carb mouths without pulling too tight. The length I bough was about 8ft.
P clips and screws or cable clips to secure the tube to the timber.
1 x rubber plumbing reducer bung. This should fit across the carb intake and make a good seal.
1 x plumbing plastic cap sized to fit in the bung.
1 x 12mm plastic hose connector
1 x 5mm plastic hose connector
1 x mig welding tip
ATF/PAS fluid.
Cut one of the tapered ends off the 5mm plastic connector. Drill a hole in the side of the 12mm plastic connector so the cut end of the 5mm connector will push in. This needs to be a tight fit, glue in place if it's loose. The small connector should protrude into the large connector so it creates a Venturi. See the 3rd photo in the above post. Drill a hole in the plastic bung to take the 12mm hose connector. Glue the connector into the bung. Add the rubber bung to the assembly to complete the carb adaptor.
Clip the tube to the timber in a u shape. You want the two vertical elements side by side so you can compare the levels. Line up one end of the tube with the top of the wood. The other should be left long to reach to the carbs. Add the ATF to the tube. When it's settled it should be about half full. The exact level isn't important. Fit the newly made carb adapter to the long end of the tube. Add the mig tip to the short end of the tube. This slows the flow slightly and provides a more stable reading.
That's the basic construction done. I'm going to upgrade mine slightly by adding some silver tape begind the tubes to make the reading easier, and use a bulldog clip to mark the level in use. I'll also add more wood to the stand skit stands up, and add a hook so I can hang it on the wall. (It should be noted, I don't know how washer tubing stands up to ATF. Don't stand it over something valuable in case it dissolves it and leaks out.)
To use. (Variable Venturi carbs)
1. Check everything is good on your engine. Even compressions, good ignition system, timing set correctly, valve clearances set correctly, carbs in good condition, no intake leaks etc.
2. Set the mixture screws to the book value. Check these are even by removing the pistons and measuring the drop from the bridge with a vernier. Adjust to match.
3. Set the idle speed by ear. You should start with each screw just making contact and wind them in the same amount from there. This should get you close to being balanced.
4. With the airbox removed, measure the flow through each carb with the manometer. Hold the adapter over the intake, ensuring you get a good seal. The Venturi in the adapter creates a depression in the manometer. There shouldn't be any flow through the manometer so the engine shouldn't ingest the atf. The adaptor shouldn't restrict the intake, so shouldn't change how the engine runs. Wait for the level to stabilise in the manometer and note the reading.
5. Switch to the 2nd carb and note the level.
6. Return to whichever carb is lower and mark the level, either with pencil on the wood or a bulldog clip.
7. Move to the high flowing carb and reduce the flow until it matches the low carb.
8. Move back to the first carb to check they're still matched. Adjust to suit.
9. If your idle speed is now too low, bring both carbs up together, using the manometer to check they still match.
10. Now repeat the process to balance the choke linkage.
11. Reassemble the airbox and go for a test drive, hopefully enjoying the benefits of synchronised carburettors.
Hope that all makes sense.
Tom